Accounting for 12 percent of U.S. industrial air pollution,
Ohio's power plants emitted 44.5 million pounds of harmful
chemicals in 2009. For comparison, the 20th ranked state, Iowa,
was responsible for just 1 percent of U.S. industrial air
pollution, or 2.5 million pounds of harmful chemicals.

The researchers also looked specifically at mercury air
pollution, finding Ohio and Pennsylvania also took the top two
spots in this measure.

The EPA is attempting to revise its public health protections to
make its Mercury and Air Toxics standard stricter, but lawmakers
including House Energy and Commerce Committee chair Fred Upton
(R-MI) have vowed to block the new measures. According to the
EPA, the proposed standards would prevent up to 120,000 cases of
childhood asthma each year and
save 17,000 lives per year by 2015.